This invention relates to a chair adjustment mechanism and to a chair incorporating such a mechanism.
Modern desk chairs have a variety of adjustments that allow the chair to be conformed to the preferences of the occupant. Commonly, such chairs allow for vertical adjustment of the backrest. In U.S. Pat. No. 5,649,741 to Beggs, a J-bar extends upwardly from the seat of the chair and receives a sleeve which is attached to the backrest. The J-bar has a vertical slot with a plurality of teeth along one side that define a rack. A pawl is positioned within the vertical slot; the pawl has a pin projecting from each of its sides into an inverted L-shaped slot in each of the front and back walls of the sleeve. The pawl is backed by a bar that is urged by a leaf spring, such that the pawl is urged into engagement with the teeth of the rack. The teeth of the pawl and of the rack are configured so that, with the pawl urged into engagement with the rack, the pawl may be ratcheted upwardly, but not downwardly. As such, the vertical position of the backrest may be selected by a user. The configuration of the vertical slot, in combination with the inverted L-shaped slots, may be used to latch the pawl out of the rack to again lower the backrest.
While the mechanism of Beggs is advantageous, a mechanism of less costly manufacture would be even more advantageous.